Conventionally, a technology for retrieving an image using a natural language has been proposed in Japanese Patent Laid-Open Publications No. HEI 4-180175, No. HEI 4-264972, No. HEI 6-176121, No. HEI 7-334507, and No. HEI 8-138075 or the like. In these publications, there is disclosed a technology in which contents of an inputted natural language are interpreted by linguistically analyzing the language such as analysis of morphophonemes there of or the like and an image matching to the contents is retrieved.
Here, an image having attribute information such as outline of the image or the like previously correlated to the image is stored in a storage, and a desired image is obtained by verifying the result of linguistic analysis of the inputted natural language with the attribute information.
As an attribute information correlated with an image to be stored, in general, filing date, name of the operator, type of the image (a photograph, a picture or text or the like) are used.
In the conventional technology as disclosed in the above publications, attribute information is previously correlated to an image as retrieval keys, so that, if any natural language relating to the attribute information is given, a desired image can be retrieved. However, since most of the attribute information is objective and minimal information required for retrieval, a user might forget the information unless he/she makes a note of it. For this reason, in a case where the user forgets the attribute information which is to be given as the retrieval key, or doubts the attribute information which the user has in his/her memory, there is a great possibility that the user may give, to a computer, data comprising a natural language far beyond the attribute information which a desired image is supposed to have, which makes it difficult to find the desired image out of an enormous amount of images.